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agula's avatar
agula
Icon for Occasional Contributor rankOccasional Contributor
5 years ago

PCIe SRIOV VF capabilities

Hi, When using virtual functions on the Arria 10 device , I notice that the virtual functions do not have the same maximum read size and maximum payload size as the physical function. Is there a wa...
Deshi_Intel's avatar
Deshi_Intel
Icon for Regular Contributor rankRegular Contributor
5 years ago

HI,


Based on what I read from the user guide doc, by right the virtual function register (PCI Express Device Capabilities Register) should be the same between physical function (PF) and virtual function (VF)


So, let's take max payload setting for example


  • page 85 - reg (0x084) - Maximum Payload Size supported by the Function. Can be configured as 000 (128 bytes) or 001 (256 bytes)
  • The setting should follow the max payload setting set in PCIe IP
  • page 24 - the only requirement in max payload setting is just to set setting > 128 if used more than 2 PF


May I know where do you see the setting difference in PF vs VF ?


Thanks.


Regards,

dlim


  • agula's avatar
    agula
    Icon for Occasional Contributor rankOccasional Contributor
    5 years ago

    I received this information through lspci -d 1172: -vv

    DevCtl under the PF capabilities shows a MPS of 256 and read request size of 4K.

    DevCtl under the VF capabilities shows a MPS of 128 and read request size of 128.

    I'm more worried about the read request size being that small. Since I need high bandwidth on all virtual functions for network interfaces.

    Thanks